Influenza (Exam 5)

RNA genome; roughly spherical capsid (pleiomorphic); viral envelope with 2 spike proteins

describe the structure of influenza virsuses

hemagglutinin (h-protein)

binds to the receptor for viral attachment and entry

neuraminidase (n-protein)

cuts the virus free of the cell during budding and release

4

how many types of influenza are there?

A or B

seasonal flu is either type __ or __

B

this type of influenza is relatively mild

children and immunosupressed

influenza B typically affects…

A

this type of influenza is moderate to severe

spike protein

influenzas are divided into subtypes based upon differences in their ________

wild aquatic birds

the primary natural reservoir for human influenza A is …

pigs, domesticated birds, infected human hosts

secondary reservoirs for influenza A

unusual function of the H-protein

the ability for Influenza to pass between multiple species of host can be attributed to…

sialic acid

the H-protein’s receptor is…

sialic acid

found on most cells of the body of most warm blooded animals

lung cells

sialic acid is found in in the greatest amounts on ______ of mammals

inside the cells of the lungs

replication of the virus occurs ____

respiratory and digestive

sialic acid can be found in the ____ & ____ tracts in birds

respiratory droplets or fluids

what is flu’s portal of exit in humans/pigs?

respiratory droplets/fluids, fecal matter

what is flu’s portal of exit in birds?

direct contact

transmission via respiratory fluids from person to person or animal contact is what type of transmission?

vehicle

type of transmission involving formites contaminated with respiratory fluids or fecal matter

airborne

type of transmission from respiratory droplets from coughing/sneezing or the airborne dusts of animal feces

eyes, nose, mouth

portal of entry in humans

primary

influenza A is a ____ pathogen

• children under 5

• elderly over 65

• pregnant/postpartum

• chronic co-morbid conditions

groups who are more susceptible to severe infection

True

True or False: viruses are limited in their virulence factors

very small; few

viral genomes are ____ (size) and have ____ (#) genes

viral reproduction causes cytopathic effects in the tissues they infect and the resulting inflammatory response

viral pathogenesis is caused by two factors

sore throat, dry cough, runny nose (rhinitis)

symptoms caused by viral replication in the respiratory tract

fever, body aches, chills, fatigue

symptoms caused by the inflammatory response to infection

antigenic variation

influenza A uses a modified form of _____ as immune evasion

subtypes

specific versions of the H&N proteins are referred to as the _____

H1N1 & H3N2

most common human influenza subtypes

it makes it’s own RNA polymerases and the genome is segmented into 8 parts

two unique features of Influenza A

False

True or False: RNA polymerases in flu are not very error prone

antigenic drift

type of change where the high mutation rate makes small changes to the spike protein sequences

antibodies

antigenic drift reduces the effectiveness of _____

more rapidly

the segmented genome allows antigenic variation to happen _____

pigs

which reservoir acts as a mixing reservoir for flu subtypes?

genetic assortment

when a host is infected with multiple subtypes, then the virus segments are packed into new viruses at random

antigenic shift

the creation of an entirely new subtype of flue with a different set of antigens

antigenic variation

the combination of antigenic shift and drift speeds up ____

trivalent

the 24-25 flu vaccine is

three different antigens

trivalent means there are ______

H1N1, H3N2, B/Victoria lineage strain

what does the 24-25 flu vaccine contain?

inactivated or subunit

what types of flu vaccines are available?